Automatic feed for feeding plywood into sanding machines



Nov. 22, 1960 a. A. HERMAN ETAL AUTOMATIC FEED FOR FEEDING PLYWOOD INTO SANDING MACHINES Filed Jan. 13, 1958 2 Sheets-Sheet 1 INVENTORS EMIL A. HERMAN Y CLYDE JOHNST N B ATTORNEYS Nov. 22, 1960 HERMAN ETAL 2,960,805

AUTOMATIC FEED FOR EEEDING PLYWOOD INTO SANDING MACHINES Filed Jan. 13, 1958 2 Sheets-Sheet 2 INVENTORS EMIL. A. HERMAN CLYDE L. JOHNSTON Y ATTORNEYS United States Patent AUTOMATIC FEED FOR FEEDING PLYWOOD INTOISANDING MACHINES Filed Jan. 13, '1958, Ser. No. 708,663

2 Claims. (Cl. 51-215) The present invention relates to an automatic feed for feeding plywood into sanding machines.

The primary object of the invention is to automatically feed one sheet of plywood at a time into a sanding machine, .Heret-ofore it required an operator to feed each sheet of plywood into a machine from a supply rack, but with this new and improved feeding device each board is fed into the sanding machine without attention from an operator.

Other objects and advantages will become apparent in the following specification when considered in the light of the attached drawings, in which:

Figure 1 is a plan view of this new and improved auto-. matic feed showing a fragmentary part of a sanding machine.

Figure 2 is a side elevation showing the cover plate of the automatic feeding mechanism removed from the cabinet.

Figure 3 is a side elevation opposite to Figure 2.

Figure 4 is a fragmentary enlarged plan view of the feeding pawl for moving the plywood forward into the sander.

FigureS is a side view. of the feeding pawl.

Figure 6 is an enlarged fragmentary sectional view, taken on the-line 66 of Figure 1, looking in the direction of the arrows.

Patented Nov. 22, 1960 connected to a pawl end 26, referring particularly to Figures 4 and 5. An offset 27 of the pawl end 26 engages end 28 of the plywood sheet 23. The opposite end of the arm is pivotally connected to a cross head 29 at 30.

The cross head 29 travels along a guide rail 31 fixedly secured to the ends 32 of the cabinet C by any suitable means. Fixedly mounted to side wall 33 of the cabinet C by clamps 34 is a pressure cylinder 35. The cylinder 35 has a piston rod 36 to the end 37 of which is fixedly secured a connecting rod 38. The opposite end of the connecting rod 38 is fixedly secured to the cross head 29.

When the piston rod 36 is moved outwardly from the cylinder 35 it will pull the cross head 29 along the rail 31 and thus move the pawl 22 and the sheet of plywood 23 in the direction of the arrow towards the feed roll *20 of the sanding machine S.

' The cylinder 35 receives a supply of air from the air supplyline 39 through a magnetic four-way valve 40. The valve 40 controls the flow of air through the pipes 41 and 42 and thus controls the direction of movement machine S for the purpose of supporting the switches Figure 7 is a diagrammatical layout, illustrating the upper sheet of plywood having been contacted and moved slightly towards the sanding machine.

Figure 8 is a view similar to Figure 7 which illustrates the same sheet of plywood moved forward and entering thefeed' rolls of the sanding machine.

Referring now to the drawings in detail wherein like reference numerals indicate like parts throughout the several figures, the reference character S indicates generally a sanding machine. A scissor type supporting jack and plywood supporting platform is indicated by the letter I; The new and improved automatic control mechanism is housed within the cabinet C.

The jack J includes a supporting platform 10, having a base 11 connected together by scissor supporting legs 12. The legs 12 are pivotally connected at 13 to one end of the platform 10 and to the base 11. Their opposite ends operating within slots 14.

A fluid cylinder 15 is pivotally mounted to the base 11 at 16 and has its piston rod 17 connected to the crank 18, keyed to a cross shaft 19. The cross shaft 19 is keyed to one pair of legs 12 and when revolved it raises the legs 12, together with the platform 10 to a higher elevation, or when turned oppositely will lower the same, positioning the plywood in the proper position for feeding a sheet at a time into the feed rolls 20 of the sanding machine S. The position of the plywood is determined by vertical stops 21 associated with the sanding machine S.

A plywood sheet feeding pawl 22 moves the upper sheet 23 from the stack of plywood 24 supported by the scissor jack I. The feeding pawl 22 includes an arm 25 integrally 44, 46, the object of which Will be later described. It has been found that where more than one switch 44, 46 is employed, in the event of warped plywood, a more reliable operating condition will exist.

The switches 44, 46 each include an operating plywood contacting roll 47 journalled on an arm'48 pivoted kit-49 to the housing 45, referring to Figure.6,causing the end 50 of the arm 48 to contact switch operating plunger 5i for opening or closing the switch 44.

The mode of operation of this new automatic plywood sheet feeding mechanism is as follows. Referring to Figure 7, in'this position the switches 44 are in closed position, and the switch 46 is in open position. When trailing edge 52 of the preceding plywood panel clears the rolls 47 of the switches 44 the switches 44 will be closed and the following electric circuit will be completed.

Energy will flow fnom the "feed conductor 53 through the switches 44 through the magnetically operated air valve 54. This will open the valve 54, allowing air to how from the supply line 55 through the valve 54 and into the cylinder 15. The object of more than one control switch 44 is that a better operating control can be maintained in the event the plywood sheet is slightly warped. When the jack J has raised the plywood to the proper elevation to feed a new sheet to the sander S, the top of the stack 24 will contact the underside of the rolls 47 of the switches 44, breaking the electric circuit through the valve 54 and stopping the upward movement of the jack and plywood.

On further movement of the trailing edge 52 of the preceding sheet of plywood, clearing the roll 47 of the switch 46 the following electric circuit will be completed.

' Energy will flow from the feed line 53 through the switch direction of the arrow, moving the sheet 23 of plywood towards thefeed rolls 20 of the sanding machine S.

When the leading edge 63 of the sheet 23 reaches the roll 47 of the switch 46 it will open an electric circuit through the conductor-56 to the relay 57, but when the relay "57 was opened the "switch bar 59' completed an electric circuit through" the solenoid 57 and conductor 64 back to the line 58, thereby'hol'ding the'relay57 in'the position shown in Figure 8, even though the leading edge 63 of the sheet 23 opened the switch '46 by raising the roll 47. This will cause the sheet of material to be'moved by the pawl 22 into the feed rolls of the sanding machine.

When the pistonrod 36 leaves the end of its travel an arm 65 will contact the switch bar 59', moving the switch bars 59 and 59 to the position shown in Figure 7, to break the electric circuit through the conductor 64 into the solenoid 57. This also opens the circuit through the conductor 60 and the solenoid 61 of the electrically operated 'four-way air valve 40 and allow the air to escape from the cylinder 35 back through the pipe 41 and out the exhaust pipe 62. Air will then pass from the pipe 39 through the valve 40 and through the pipe line 42, moving the piston rod 36 to the left returning the pawl 20 to its starting position, as shown in Figure 7, completing a cycle of operation.

The electro-magnetic four-way valve .40 is positioned to move the piston rod 36 to the right by action of solenoid 61 and reversed to move the piston rod 36 to the left by action of a spring (not shown) within the valve 40. The valve 40 is of conventional design readily available on the commercial market.

Having thus described the preferred embodiment of the invention, it should be understood that numerous structural modifications and adaptations may be resorted to without departing from the scope of the appended claims.

What is claimed is:

'1. In combination with a conventional machine for sanding sheets of plywood or the like, said machine having a sheet intake means; a feeding mechanism for .delivering sheets one at a time to said sheet intake means, a sheet'stack support, power driven means associated with said support for advancing the topmost sheet on said stack toward the intake means of said sanding machine, said power driven means including a reciprocatory feeding pawl engageable during its advancing stroke with the rear edge of the uppermost sheet near one trailing corner thereof, said feeding mechanism also including a guide rail positioned to guide the leading corner of said sheet opposite from said trailing corner while said sheet advances into the intakemeans of said sanding machine, and mechanism for guiding said feeding pawl during its advancing stroke to generate a slight lateral movement of said topmost sheet, such feeding pawl guiding mechanism including a camway disposed at a slight angle to the direction of advance of said sheet, and a cam follower on said feeding pawl, such lateral movement of said feeding pawl as is generated by said camway and said cam follower facilitating advancement of said topmost sheet from the sheet on which it rests without disturbance of the position of the latter.

2. In combination with a conventional machine for sanding sheets of plywood or the like, said machinehaving sheet intake means and a conventional, vertically movable upper section; a feeding mechanism for delivering sheets one at a time to said sheet intake means, a sheet stack support, a first power means for vertically moving said stack support, and a second power means for advancing the uppermost sheet on said stack toward the intake means of said sanding machine, said mechanism further comprising a first feeler means mounted on the intake means of said sanding machine andengaging the uppermost sheet of said stack, a second feeler means also mounted on the intake means of said sanding machine and engaging said uppermost sheet as the same advances toward said intake means, control means actuated by said first feeler means on removal of the upermost sheet from said stack to energize said first power means and cause the then uppermost sheet of said stack to be elevated substantially to the level of said sanding machine intake means, and control means actuated by said second feeler means on movement of the trailing edge of an advancing sheet past said second feeler means to energize said second power means and cause the then uppermost sheet on said stack to be advanced into said sanding machine infeed means, said first and second feeler meansbeing mounted on the vertically movable uppersection of said sanding machine so as to move therewith and automatioally compensate for variations in thickness of successive sheets fed to said sanding machine by said feeding mechanism when the thickness setting of said sanding machine is varied.

References Cited in the file of this patent UNITED STATES PATENTS 282,014 Stuart July 24, 1883 1,174,739 Langston ..-Mar. 7, 1916 1,833,292 Kirck Nov. 24, 1931 2,076,186 Reynolds et al. Apr. 6, 1937 2,266,596 Goodwin Dec. 16,1941 2,467,493 Pabich Apr. 1-9, 1949 2,595,015 Sparks Apr. 29,1952 

